1. Field of the Invention
This invention relates, generally, to catamarans. More particularly, it relates to a catamaran having elongate tubular air scoops positioned beneath the deck above the water line.
2. Description of the Prior Art Sponson-Vaka Aka-Top of the Tunnel or Wing
A catamaran is defined in Webster as a twin hulled watercraft with a deck or superstructure interconnecting the hulls. Wikipedia defines a catamaran as a multi-hulled watercraft where each sponson is called a vaka and the top of the tunnel or wing that interconnects the vakas is called the aka.
Catamarans ride on a bubble of air when traveling at high speeds. A ribbon placed on the bow that extends into the cavity below the aka and between the vakas above the water will flow toward the stern at slow speeds. As the speed increases, pressure builds up under the aka. When the speed attains a certain threshold, depending upon the structure and speed of the craft, the ribbon blows out of the air space under the aka and extends in leading relation to the craft.
The forward flowing ribbon is caused by the high air pressure in the tunnel, i.e., the space under the aka. As speed increases, a catamaran rises as the air pressure in the aka rises. A catamaran balances at its center of gravity and the watercraft lifts evenly from the water so that the bow and stern are lifted together.
At relatively low speeds, the vaka provide buoyancy just like the hull of a conventional watercraft. As speed increases, the vaka begin to rise from the water but the bubble of high pressure air in the aka builds up and collapses frequently until a high speed is obtained. The build-up and collapsing of the air bubble in the aka causes the watercraft to buck, kick, and shimmy, creating an uncomfortable ride. When a sufficiently high speed is attained, the vaka rise to the surface of the water and they no longer perform the flotation function provided at lower speeds. The air bubble build-up and collapse pattern ends and the ride becomes smooth. At such high speed, a catamaran can turn without banking; the vaka provide stability instead of buoyancy.
In conventional catamarans, the air bubble build-up and collapse begins at about sixty five miles per hour (65 mph), depending upon the size, design, and weight of the craft, and the smooth ride does not resume until the craft reaches a speed of about ninety five to one hundred ten miles per hour (95-110 mph). The time that the air bubble is building up and collapsing is known as the transition time.
There is a need for a new catamaran design that substantially reduces or eliminates the transition time. By increasing the size of the aka, the vaka should begin to rise from the water at a lower speed and rise to the surface of the water at a lower speed as well. Even if the transition time is not completely eliminated, the bucking and kicking of the craft during the transition time would thereby be reduced.
Moreover, a transition time that begins and ends at lower speeds increases the efficiency of the craft, i.e., getting into the smooth portion of the ride, where the vaka have risen to the water surface, as soon as possible provides a great advantage in racing events and increases the comfort of the passenger or passengers as well due to the reduction or elimination of the transition time.
However, in view of the prior art taken as a whole at the time the present invention was made, it was not obvious to those of ordinary skill how the identified needs could be fulfilled.